An Efficient Route to Pyrimidine Nucleoside Analogues by [4+ 2

An Efficient Route to Pyrimidine Nucleoside Analogues by [4 + 2] Cycloaddition Reaction Morwenna S. M. Pearson,† Ae´lig Robin,† Nathalie Bourgougnon,‡ Jean Claude Meslin,† and David Deniaud*,† Laboratoire de Synthe` se Organique, UMR CNRS 6513, Faculte´ des Sciences et des Techniques, 2, Rue de la Houssinie` re 44322 Nantes Cedex 03, France, and Laboratoire de Biologie Mole´ culaires EA 2594, Centre de recherche et d’enseignemant Yves Coppens, Campus de Tohannic, BP 573, 56017 Vannes, France [email protected] Received May 26, 2003

We report here an efficient synthesis for pyrimidine nucleoside analogues by [4 + 2] cycloaddition reaction. These compounds were obtained by convergent chemistry from glycosyl isothiocyanates 3a-f (pyranoses, furanoses, and dissaccharides) and diazadienium salt 5. In fact, diazapentadienium iodide 5 prepared from vinylthioamide 4 is an efficient intermediate in heterocyclic synthesis and reacts with isothiocyanates 3a-f affording β-D-uracil analogues 7a-f in good yields and with total regiocontrol. All compounds were fully characterized by IR, HRMS, and 13C and 1H NMR (COSY and HMQC). Introduction For many years, modified nucleosides have been widely used as antiviral and antitumor agents.1 Considerable efforts have been undertaken to exploit synthetic routes to these compounds.2 In the course of the preparation of nucleosides, base moieties are generally introduced by substitution or more rarely by construction.3 Conventionally, synthesis of N-linked oligosaccharides has been achieved by coupling of activated glycosyl derivatives with heterocyclic nucleobase analogues such as pyrimidinones.4 Alternative methods for N-alkylation include heating with trimethyl phosphate5 and alkylation of O-silylated derivatives,6 which is an important method for unambiguous N-alkylation especially ribosylation of uracils.7 Complementary studies through an intramo†

Universite´ de Nantes. Universite´ de Bretagne Sud. (1) (a) Garg, R.; Gupta, S.; Gao, H.; Babu, M.; Debnath, A.; Hansch, C. Chem. Rev. 1999, 99, 3523. (b) Hurin, D. N.; Okabe, M. Chem. Rev. 1992, 92, 1745. (c) Lin, T. S.; Luo, M. Z.; Liu, M. C.; Zhu, Y. L.; Gullen, E.; Dutschman, G. E.; Cheng, Y. C. J. Med. Chem. 1996, 39, 1757. (d) Webb, T. R.; Mitsuya, H.; Broder, S. J. Med. Chem. 1988, 31, 1475 and references therein. (2) (a) Zorbach, W. W. Synthesis 1970, 7, 329. (b) Kahne, D.; Walker, S.; Cheng, Y.; Van Engen, D. J. Am. Chem. Soc. 1989, 111, 6881. (c) Ichikawa, E.; Kato, K. Curr. Med. Chem. 2001, 8, 385. (d) Komatsu, H.; Araki, T. Tetrahedron Lett. 2003, 44, 2899. (e) Trelles, J. A.; Fernandez, M.; Lewkowicz, E. S.; Iribarren, A. M.; Sinisterra, J. V. Tetrahedron Lett. 2003, 44, 2605. (3) Ane´, A.; Prestat, G.; Manh, G. T.; Josse, S.; Pipelier, M.; Lebreton, J.; Prade`re, J. P.; Dubreuil, D. Pure Appl. Chem. 2001, 73, 1189. (4) (a) Plimil, J.; Prystas, M. Adv. Heterocycl. Chem. 1967, 8, 115. (b) Niedballa, U.; Vorbruggen, H. J. Org. Chem. 1974, 39, 3672. (c) Vorbruggen, H.; Krolikiewicz, K.; Bennua, B. Chem. Ber. 1981, 114, 1234. (d) Vorbruggen, H.; Hofle, G. Chem. Ber. 1981, 114, 1256. (e) Sugimura, H.; Muramoto, I.; Nakamura, T.; Osumi, K. Chem. Lett. 1993, 169. (f) Jungmann, O.; Pfleiderer, W. Tetrahedron Lett. 1996, 37, 8355. (5) Yamauchi, M.; Kinoshita, M. J. Chem. Soc., Perkin Trans. 1 1973, 8, 391. (6) Mu¨ller, C. E. Tetrahedron Lett. 1991, 32, 6539. ‡

lecular transposition process were investigated in order to improve the synthesis of nucleoside pyrimidinone analogues.8 Significant and diverse pharmaceutical values of various nucleosides have inspired investigations toward the development of new synthetic methods for their practical preparation. Among the N-glycosides, glycosyl isothiocyanates are attracting much attention because of the synthetic flexibility of the isothiocyanate function.9 In fact, sugar isothiocyanates play a key role in the preparation of a variety of functional groups as well as in the construction of heterocyclic ring systems. In particular, they have been used for the synthesis of a wide spectrum of carbohydrate derivatives with thiourea structure.10 Recently, glycosyl isothiocyanates were used to prepare galactofuranosidase inhibitors,11 β-amphiphilic compounds,12 hydantocidin,13 spironucleosides,14 and glycodendrimers.15 Paradoxically, only few syntheses of nucleoside analogues by [4 + 2] (7) Matsuda, A.; Kurasawa, Y.; Watanabe, K. Synthesis 1981, 9, 748. (8) (a) Jung, M. E.; Castro, C. J. Org. Chem. 1993, 58, 507. (b) Sujino, K.; Sugimura, H. Chem. Lett. 1993, 1187. (c) Lipshutz, B. H.; Stevens, K. L.; Lowe, R. F. Tetrahedron Lett. 1995, 36, 2711. (d) Xia, X.; Wang, J.; Hager M. W.; Sisti, N.; Liotta, D. C. Tetrahedron Lett. 1997, 38, 1111. (e) Sugimura, H.; Katoh, Y. Chem. Lett. 1999, 361. (9) (a) Mukerjee, A. K.; Ashare, R. Chem. Rev. 1991, 91, 1. (b) Al Massoudi, N.; Hassan, N. A.; Al-Soud, Y. A.; Schmidt, P.; Gaafar, A. E.-D.; Weng, M.; Marino, S.; Schoch, A.; Amer, A.; Jochins, J. C. J. Chem. Soc., Perkin Trans. 1 1998, 5, 947. (10) Saleh, M. A. Nucleosides, Nucleotides Nucleic Acids 2002, 21, 401. (b) Benito, J. M.; Ortiz Mellet, C.; Sadalapure, K.; Lindhorst, T. K.; Defaye, J.; Garcia Ferna´ndez, J. M. Carbohydr. Res. 1999, 320, 37. (c) Dı´az Pe´rez, V. M.; Ortiz Mellet, C.; Fuentes, J.; Garcia Ferna´ndez, J. M. Carbohydr. Res. 2000, 326, 161. (d) Fuentes, J.; Moreda, W.; Ortiz, C.; Robina, I.; Welsh, C. Tetrahedron 1992, 48, 6413. (11) Marino, C.; Herczegh, P.; de Lederkremer, R. M. Carbohydr. Res. 2001, 333, 123. (12) Prata, C.; Mora, N.; Polidori, A.; Lacombe, J.-M.; Pucci, B. Carbohydr. Res. 1999, 321, 15. (13) (a) Shiozaki, M. Carbohydr. Res. 2001, 335, 147. (b) Shiozaki, M. Carbohydr. Res. 2002, 337, 2077.

10.1021/jo034709a CCC: $25.00 © 2003 American Chemical Society

Published on Web 10/01/2003

J. Org. Chem. 2003, 68, 8583-8587

8583

Pearson et al. SCHEME 1.

Synthetic Route to Nucleosides 7a-f

cycloaddition or addition-cyclization reactions of glycosyl isothiocyanates have been described.14a,16 Therefore, it would be interesting to establish simple synthetic approaches and novel concepts in the synthesis and development of pyrimidine nucleoside analogues. During the last years, we have focused our research on the development of efficient methodologies to build heterocyclic compounds.17 In our previous paper, we described the versatility of cationic dienes as stable synthons for the preparation of various heterocyclic rings.18 We report here the reactivity of diazadienium iodide 5 in a [4 + 2] cycloaddition reaction with glycosyl isothiocyanates 3a-f affording sugar pyrimidines 7a-f (Scheme 1).19 This type of derivatives opens a new route to original functionalized six-membered ring heterocycles with strong biological potential. Results and Discussion Starting glycosyl isothiocyanates 3a-f were obtained in two steps in good to moderate overall yields. Thus, acetylated (for 3a-d) or benzoylated (for 3e,f) glycosyl bromides were prepared by stirring the respective acetates in HBr-acetic acid solution.20 A subsequent step in a phase-transfer reaction using thiocyanate anion and tetrabutylammonium bromide as catalyst in acetonitrile (14) (a) Fuentes, J.; Molina, J. L.; Pradera, M. A. Tetrahedron: Asymmetry 1998, 9, 2517. (b) Gasch, C.; Pradera, M. A.; Salameh, B. A. B.; Molina, J. L.; Fuentes, J. Tetrahedron: Asymmetry 2001, 12, 1267. (c) Gasch, C.; Salameh, B. A. B.; Pradera, M. A.; Fuentes, J. Tetrahedron Lett. 2001, 42, 8615. (15) (a) Andre´, S.; Pieters, R. J.; Vrasidas, I.; Kaltner, H.; Kuwabara, I.; Liu, F.-T.; Liskamp, R. M. J.; Gabius, H.-J. ChemBioChem 2001, 2, 822. (b) Vrasidas, I.; de Mol, N. J.; Liskamp, R. M. J.; Pieters, R. J. Eur. J. Org. Chem. 2001, 4685. (16) (a) Takahashi, H.; Nimura, N.; Ogura, H. Chem. Pharm. Bull. 1979, 27, 1143. (b) Valentı´ny, M.; Martvon, A.; Kova´c, P. Collect. Czech. Chem. Commun. 1981, 46, 2197. (c) Ogura, H.; Takahashi, H.; Sato, O. Chem. Pharm. Bull. 1981, 29, 1838. (17) (a) Charrier, J. D.; Landreau, C.; Deniaud, D.; Reliquet, A.; Reliquet, F.; Meslin, J. C. Tetrahedron 2001, 57, 4195. (b) Landreau, C.; Deniaud, D.; Reliquet, A.; Meslin, J. C. Synthesis 2001, 13, 2015. (c) Landreau, C.; Deniaud, D.; Reliquet, A.; Meslin, J. C. Synthesis 2002, 3, 403. (d) Landreau, C.; Deniaud, D.; Evain, M.; Reliquet, A.; Meslin, J. C. J. Chem. Soc., Perkin Trans. 1 2002, 6, 741. (e) Landreau, C.; Deniaud, D.; Reliquet, A.; Meslin, J. C. Phosphorus, Sulfur Silicon 2002, 177, 2651. (f) Landreau, C.; Deniaud, D.; Reliquet, A.; Meslin, J. C. Tetrahedron Lett. 2002, 43, 4099. (g) Landreau, C.; Deniaud, D.; Reliquet, A.; Meslin, J. C. Eur. J. Org. Chem. 2003, 3, 421. (h) Landreau, C.; Deniaud, D.; Meslin, J. C. J. Org. Chem. 2003, 68, 4912. (18) (a) Friot, C.; Reliquet, A.; Reliquet, F.; Meslin, J. C. Synthesis 2000, 5, 695. (b) Landreau, C.; Deniaud, D.; Reliquet, A.; Reliquet, F.; Meslin, J. C. J. Heterocycl. Chem. 2001, 38, 93. (19) (a) Ueda, T.; Iida, Y.; Ikeda, K.; Mizumo, Y. Chem. Pharm. Bull. 1968, 16, 1788. (b) Ueda, T.; Nishino, H. Chem. Pharm. Bull. 1969, 17, 920. (c) Bretner, M.; Felczak, K.; Dzik, J. M.; Golos, B.; Rode, W.; Drabikowska, A.; Poznanski, J.; Krawiec, K.; Piasek, A.; Shugar, D.; Kulikowski, T. Nucleosides Nucleotides 1997, 16, 1295. (20) Koch, A.; Lamberth, C.; Wetterich, F.; Giese, B. J. Org. Chem. 1993, 58, 1083.

8584 J. Org. Chem., Vol. 68, No. 22, 2003

in the presence of molecular sieves (4 Å) afforded the desired N-glycosides 3a-f (Scheme 2) without yielding corresponding thiocyanates.21,22 The reaction is totally diastereoselective affording only the 1,2-trans-isothiocyanates, probably due to the anchimeric participation of the vicinal 2-O-acyl group.21a,23 The anomeric configuration could be easily determined by measuring the anomeric coupling constant J1,2. The J1,2 value (∼8.4 Hz) indicated pyranoses 3a-d to be β. The β-D-furanose configuration of 3e,f was equally established by means of H1-H2 coupling constant values, which being smaller than 1 Hz indicate a 1,2-trans relationship.24 Compounds 2e,f were reacted directly with an excess of potassium thiocyanate without purification. In fact, 2,3,5-tri-Obenzoyl-D-ribofuranosyl bromide 2e and 2,3,5-tri-O-benzoyl-D-xylofuranosyl bromide 2f proved extremely unstable and degraded on silica gel during chromatography. Rajappa and Advani have previously reported the condensation of N,N-dimethylformamide dimethyl acetal and thioacetamide to furnish vinylthioamide 4 in very poor yields (6.5%).25 An alternative preparation consisting of sulfhydratation of the commercially available 3-dimethylaminoacrylonitrile (trans/cis ratio: 95/5) in the presence of triethylamine and pyridine permitted the isolation of compound 4 in more satisfactory yields (79%), and with exclusive E configuration (Scheme 3). During the past years, different types of 2-amino-1thiazabutadienes have been studied in our laboratory. We have reported that these compounds could react either as thiazadienes or diazadienes giving rise to tetrahydropyrimidines or 1,3-thiazines.18a,26 Vinylthioamide 4 can have also two tautomeric forms either azadiene or thiadiene, and thus probably possess a wide reactivity. With the aim to investigate the synthesis of uracil analogues, we have rigidified the structure by alkylation of compound 4 to obtain only the azadiene chain. Alkylation of vinylthioamide afforded, as the sole product, the corresponding S-methyl salt 5, due to the higher nucleophilicity of the sulfur. In contrast to the method developed in the literature, we never observed a dehydrohalogenation of iodide 5 in the basic medium to afford methylthioimine.26a,27 In this case, the expected product was not stable enough to be isolated (Scheme 3). This problem was solved by the use of the cationic form. In fact, the reaction of diazadienium iodide 5 in a [4 + 2] cycloaddition reaction with glycosyl isothiocyanates 3a-f afforded methylsulfanyldihydropyrimidinethiones 7a-f in good yields (Table 1). In this reaction, the intermediate 6 was never isolated and the final step consisted in a (21) (a) Camarasa, M. J.; Fernandez-Resa, P.; Garcia-Lopez, M. T.; de las Heras, F. G.; Mendez-Castrillon, P. P.; San Felix, A. Synthesis 1984, 6, 509. (b) Kassab, R.; Fe´lix, C.; Parrot-Lopez, H.; Bonaly, R. Tetrahedron Lett. 1997, 38, 7555. (22) (a) Lindhorst, T. K.; Kieburg, C. Synthesis 1995, 10, 1228. (b) Somsa´k, L.; Czifra´k, K.; Deim, T.; Szila´gyi, L.; Be´nyei, A. Tetrahedron: Asymmetry 2001, 12, 731. (23) Marino, C.; Varela, O.; de Lederkremer, R. M. Carbohydr. Res. 1997, 304, 257. (24) (a) Bundle, D. R.; Lemieux, R. D. Methodol. Carbohydr. Chem. 1976, 7, 79. (b) Marino, C.; Varela, O.; de Lederkremer, R. M. Carbohydr. Res. 1989, 190, 65. (c) de Lederkremer, R. M.; Nahmad, V. B.; Varela, O. J. Org. Chem. 1994, 59, 690. (25) Rajappa, S.; Advani, B. G. Indian J. Chem., Sect. B 1978, 16, 819. (26) (a) Friot, C.; Reliquet, A.; Reliquet, F.; Meslin, J. C. Phosphorus, Sulfur Silicon 2000, 156, 135. (b) Landreau, C.; Deniaud D.; Reliquet, A.; Reliquet, F.; Meslin, J. C. Heterocycles 2000, 53, 2667. (27) Mazumdar, S. N.; Mahajan, M. P. Synthesis 1990, 5, 417.

Efficient Route to Pyrimidine Nucleoside Analogues SCHEME 2.

a

Synthetic Route to Glycosyl Isothiocyanates 3a-fa

Reagents and conditions: (i) CH2Cl2, HBr in AcOH, 0°C, 2 h; (ii) CH3CN, KSCN, molecular sieves 4 Å, Bu4N+ Br-, reflux, 2 h.

SCHEME 3.

Synthesis of S-Methyl Salt 5a

SCHEME 4.

Synthesis of N-Nucleosides 7a-fa

a Reagents and conditions: (i) Et N, pyridine, H S, rt, 48 h; (ii) 3 2 CH3I, THF, rt, 18 h.

TABLE 1. Yields of Compounds 7a-f and Selected NMR Data (δ, ppm; J, Hz)) compd

sugar

yielda (%)

H-1 (J)

C-1

7a 7b 7c 7d 7e 7f

glucosyl galactosyl cellobiosyl lactosyl ribosyl xylosyl

84 82 82 73 72 83

7.23 (9.5) 7.21 (8.3) 7.14 (9.2) 7.28 (8.9) 7.22 (3.0) 6.79

85.7 86.2 87.0 86.4 92.0 94.2

a

Isolated yields. Yields of 7a-f are based on diazadienium 5.

deamination of the formed cycloadduct giving sugar pyrimidines 7a-f (Scheme 4). Starting from salt 5, triethylamine can be added to remove hydriodic acid. This [4 + 2] cycloaddition reaction occurs in a regiocontrolled manner. The structures of compounds 7a-f were determined unequivocally by the complementary of the 1H/13C-2D NMR techniques (COSY and HMQC) (Table 1). The β anomeric configuration was fully preserved, and we observed only 1,2-trans glycosidic linkage. In this reaction, the dimethylamine generated in the mixture reacted with a second equivalent of the dienophile to provide glycosyl thioureas 8a-f. These types of N-nucleosides may be attracting much attention from the viewpoint of antiviral and antitumor drugs. Preliminary biological tests (antiviral and cytotoxicity assays) with pyrimidine glycoside 7a against Herpes simplex virus type 1 (HSV-1) showed a significant

a

Reagents and conditions: (i) CH2Cl2, Et3N, rt, 3 h.

in vitro activity.28 Their evaluation as antitumor agents is in progress, and these promising results led us to develop new N-nucleosides. In summary, we have developed an effective method for the synthesis of various pyrimidine nucleoside analogues by [4 + 2] cycloaddition reaction between glycosyl isothiocyanates and diazadienium iodide. Advantages of the present method are: easy availability of starting materials, good yields in the [4 + 2] cycloaddition reaction, high diastereoselectivity and regioselectivity, and experimental simplicity of the procedure. Substitution of methylsulfanyl group using diverse nucleophiles is now under investigation.

Experimental Section 2-Amino-4-(dimethylamino)-1-thiabuta-1,3-diene (4). Hydrogen sulfide was passed at room temperature for 4 h through a solution of 3-dimethylaminoacrylonitrile (3.84 g, 40 (28) Cytotoxic effect of pyrimidine glycoside 7a on the Vero cells was not observed in the range of the concentrations tested. After 3 days of treatment, 39% cellular destruction was observed at 200 µg/mL (CC50 > 200 µg/mL). Compound 7a is efficient against HSV-1 in vitro. 59% cellular protection was obtained for 200 µg/mL 72 h after infection (EC50 111.20 µg/mL).

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Pearson et al. mmol) in triethylamine (25 mL) and pyridine (25 mL). The solvents were removed, and the residue was crystallized from dichloromethane then methanol to provide 4 as a white solid (4.12 g, 31.7 mmol, 79%). Mp: 189-191 °C. IR (KBr): 3342, 1605, 1344, 1116 cm-1. 1H NMR (DMSO-d6) δ: 2.88 (br s, 6H, N(CH3)2), 5.20 (d, 1H, J ) 12.2 Hz, CHCS), 7.69 (d, 1H, J ) 12.2 Hz, CHN), 7.85 (br s, 1H, NH2), 7.99 (br s, 1H, NH2). 13C NMR (DMSO-d6) δ: 38.7 and 43.76 (N(CH3)2), 96.4 (CHCS), 155.2 (CHN), 194.6 (CS). MS: m/z 130 (M+, 100), 97 [M SH]+, 86 (10). Anal. Calcd for C5H10N2S: C, 46.12; H, 7.74; N, 21.51. Found: C, 46.34; H, 7.54; N, 21.74. 1,1-Dimethyl-4-methylsulfanyl-1,5-diazapentadienium Iodide (5). A suspension of thiabutadiene 4 (1 g, 7.7 mmol) in methyl iodide (6 mL) and tetrahydrofuran (6 mL) was stirred for 18 h at room temperature. The mixture was evaporated under reduced pressure. After addition of diethyl ether (40 mL), compound 5 was precipitated and collected by filtration to leave a white solid, which was dried under vacuum (2.02 g, 74.3 mmol, 96%). Mp: 182-184 °C. IR (KBr): 3257, 3107, 1632, 1533, 1282, 1056 cm-1. 1H NMR (D2O) δ: 2.55 (s, 3H, CH3S), 3.03 (s, 3H, N(CH3)2), 3.27 (s, 3H, N(CH3)2), 5.36 (d, 1H, J ) 12.2 Hz, CHCS), 7.95 (d, 1H, J ) 12.2 Hz, CHN). 13 C NMR (D2O) δ: 13.1 (CH3S), 37.5 and 45.6 (N(CH3)2), 89.2 (CHCS), 156.7 (CHN), 176.3 (CSCH3). Anal. Calcd for C6H13IN2S: C, 26.48; H, 4.81; N, 10.29. Found: C, 26.22; H, 5.03; N, 10.97. Pyrimidine Nucleoside (7). Diazapentadienium iodide 5 (0.42 mmol) was added to a solution of glycoside isothiocyanates 3a-f (0.85 mmol) in dichloromethane (20 mL). After 1 h of stirring at room temperature, the reaction mixture was cooled to 0 °C, and triethylamine (0.85 mmol) was added. The mixture was stirred at room temperature for an additional 2 h, and then the solvent was removed in vacuo. The resulting residue was partitioned between CH2Cl2 (20 mL) and water (2 × 20 mL). The organic extract was dried (MgSO4), filtered, and evaporated. The residue was purified by flash chromatography on silica using hexane/AcOEt (9/1) and then hexane/ AcOEt (4/6) mixture as eluent to give compounds 7 and 8. 1-(2,3,4,6-Tetra-O-acetyl-β-D-glucopyranosyl)-4-methylsulfanyl-1,2-dihydropyrimidin-2-thione (7a). Yellow crystals (yield 84%). Mp: 94-96 °C. IR (KBr): 1753, 1612, 1492, 1223 cm-1. 1H NMR (CDCl3) δ: 2.00 (s, 3H, COCH3), 2.02 (s, 3H, COCH3), 2.06 (s, 3H, COCH3), 2.08 (s, 3H, COCH3), 2.60 (s, 3H, CH3S), 4.01 (ddd, 1H, J ) 9.5, 5.1, 2.0 Hz, glu H5), 4.10 (dd, 1H, J ) 12.6, 2.0 Hz, glu H6b), 4.29 (dd, 1H, J ) 12.6, 5.1 Hz, glu H6a), 5.14 (t, 2H, J ) 9.5 Hz, glu H2 and H4), 5.49 (t, 1H, J ) 9.5 Hz, glu H3), 6.56 (d, 1H, J ) 7.2 Hz, H5 pyr), 7.23 (d, 1H, J ) 9.5 Hz, glu H1), 7.49 (d, 1H, J ) 7.2 Hz, H6 pyr). 13 C NMR (CDCl3) δ: 13.1 (CH3S), 20.5 and 20.7 (4 COCH3), 61.6 (glu C6), 67.9 and 71.0 (glu C2 and C4), 72.4 (glu C3), 75.2 (glu C5), 85.7 (glu C1), 108.6 (C5 pyr), 139.4 (C6 pyr), 169.6, 170.0, 170.5 and 173.1 (4 COCH3 and CdN), 181.3 (CdS). MS: m/z 489 ([M + H]+), 331 (100). HRMS (CI): m/z calcd for C19H25N2O9S2 [M + H]+ 489.1002, found 489.1005. 1-(2,3,4,6-Tetra-O-acetyl-β-D-galactopyranosyl)-4-methylsulfanyl-1,2-dihydropyrimidin-2-thione (7b). Yellow crystals (yield 82%). Mp: 93-95 °C. IR (KBr): 1749, 1613, 1493, 1224 cm-1. 1H NMR (CDCl3) δ: 2.01 (s, 3H, COCH3), 2.03 (s, 3H, COCH3), 2.06 (s, 3H, COCH3), 2.20 (s, 3H, COCH3), 2.62 (s, 3H, CH3S), 4.11-4.22 (m, 2H, gal H6a and H6b), 4.13 (dd, 1H, J ) 7.1, 2.7 Hz, gal H4), 5.27-5.31 (m, 1H, gal H5), 5.29 (dd, 1H, J ) 8.3, 0.8 Hz, gal H2), 5.54 (dd, 1H, J ) 2.7, 0.8 Hz, gal H3), 6.58 (d, 1H, J ) 7.3 Hz, H5 pyr), 7.21 (d, 1H, J ) 8.3 Hz, gal H1), 7.54 (d, 1H, J ) 7.3 Hz, H6 pyr). 13C NMR (CDCl3) δ: 13.1 (CH3S), 20.5 and 20.7 (4 COCH3), 61.2 (gal C6), 67.0 (gal C3), 68.7 (gal C2), 70.6 (gal C5), 74.1 (gal C4), 86.2 (gal C1), 108.6 (C5 pyr), 139.8 (C6 pyr), 169.0 and 170.4 (4 COCH3 and CdN), 180.0 (CdS). MS: m/z 489 ([M + H]+), 331 (100). HRMS (CI): m/z calcd for C19H25N2O9S2 [M + H]+ 489.1002, found 489.0999. 1-(2,3,6,2′,3′,4′,6′-Hepta-O-acetyl-β-D-cellobiopyranosyl)4-methylsulfanyl-1,2-dihydropyrimidin-2-thione (7c). Yel-

8586 J. Org. Chem., Vol. 68, No. 22, 2003

low crystals (yield 82%). Mp: 124-126 °C. IR (KBr): 1750, 1613, 1493, 1228 cm-1. 1H NMR (CDCl3) δ: 1.99 (s, 3H, COCH3), 2.00 (s, 3H, COCH3), 2.01 (s, 3H, COCH3), 2.03 (s, 3H, COCH3), 2.04 (s, 3H, COCH3), 2.10 (s, 3H, COCH3), 2.12 (s, 3H, COCH3), 2.60 (s, 3H, CH3S), 3.68 (ddd, 1H, J ) 9.4, 4.5, 2.2 Hz, glu H5′), 3.85 (dd, 1H, J ) 10.3, 9.2 Hz, glu H4), 3.93 (ddd, 1H, J ) 10.3, 5.5, 1.6 Hz, glu H5), 4.04 (dd, 1H, J ) 12.5, 2.2 Hz, glu H6′b), 4.15 (m, 1H, glu H6b), 4.35 (dd, 1H, J ) 12.5, 4.5 Hz, glu H6′a), 4.48 (dd, 1H, J ) 12.2, 1.6 Hz, glu H6a), 4.55 (d, 1H, J ) 8.0 Hz, glu H1′), 4.94 (dd, 1H, J ) 9.4, 8.0 Hz, glu H2′), 5.08 (t, 1H, J ) 9.2 Hz, glu H2), 5.10 (t, 1H, J ) 9.4 Hz, glu H4′), 5.18 (t, 1H, J ) 9.4 Hz, glu H3′), 5.47 (t, 1H, J ) 9.2 Hz, glu H3), 6.51 (d, 1H, J ) 7.3 Hz, H5 pyr), 7.14 (d, 1H, J ) 9.2 Hz, glu H1), 7.41 (d, 1H, J ) 7.3 Hz, H6 pyr). 13C NMR (CDCl3) δ: 14.3 (CH3S), 21.7 and 22.0 (7 COCH3), 62.8 and 63.0 (glu C6′ and C6), 69.0 (glu C2), 72.1 (glu C5′), 72.1 (glu C4′), 73.0 (glu C2′), 73.3 (glu C3), 74.0 (glu C3′), 77.2 (glu C4 and C5), 87.0 (glu C1), 101.7 (glu C1′), 109.6 (C5 pyr), 140.4 (C6 pyr), 170.2, 170.5, 171.4 and 171.7 (7 COCH3 and CdN), 183.0 (Cd S). MS: m/z 777 ([M + H]+), 717 (100), 331. HRMS (DCI): m/z calcd for C31H41N2O17S2 [M + H]+ 777.1847, found 777.1851. 1-(2,3,6,2′,3′,4′,6′-Hepta-O-acetyl-β-D-lactopyranosyl)-4methylsulfanyl-1,2-dihydropyrimidin-2-thione (7d). Yellow crystals (yield 73%). Mp: 131-133 °C. IR (KBr): 1753, 1613, 1493, 1226 cm-1. 1H NMR (CD3COCD3) δ: 1.92 (s, 3H, COCH3), 1.94 (s, 3H, COCH3), 2.07 (s, 3H, COCH3), 2.09 (s, 3H, COCH3), 2.10 (s, 3H, COCH3), 2.11 (s, 3H, COCH3), 2.16 (s, 3H, COCH3), 2.59 (s, 3H, CH3S), 4.17-4.29 (m, 6H, glu H4, H5, H6b and gal H5, H6a, H6b), 4.64 (d, 1H, J ) 10.3 Hz, glu H6a), 4.94 (m, 1H, gal H1), 5.08-5.15 (m, 2H, gal H2 and H3), 5.25 (t, 1H, J ) 8.9 Hz, glu H2), 5.39 (s, 1H, gal H4), 5.58 (t, 1H, J ) 8.9 Hz, glu H3), 6.81 (d, 1H, J ) 7.1 Hz, H5 pyr), 7.28 (d, 1H, J ) 8.9 Hz, glu H1), 8.06 (d, 1H, J ) 7.1 Hz, H6 pyr). 13 C NMR (CD3COCD3) δ: 12.8 (CH3S), 20.6 (7 COCH3), 61.9 (gal C6), 62.9 (glu C6), 68.1 (gal C5), 69.9 (gal C4), 71.5 and 71.7 (gal C2 and C3), 72.5 (glu C2 and C3), 76.7 (glu C4 and C5), 86.4 (glu C1), 101.6 (gal C1), 108.6 (C5 pyr), 142.4 (C6 pyr), 169.6, 169.8, 170.2, 170.8 and 171.5 (7 COCH3 and CdN), 182.0 (CdS). MS: m/z 777 ([M + H]+), 71, 559, 331 (100). HRMS (DCI): m/z calcd for C31H41N2O17S2 [M + H]+ 777.1847, found 777.1836. 1-(2,3,5-Tri-O-benzoyl-β-D-ribofuranosyl)-4-methylsulfanyl-1,2-dihydropyrimidin-2-thione (7e). Yellow crystals (yield 72%). Mp: 89-91 °C. IR (KBr): 1727, 1601, 1450, 1269 cm-1. 1H NMR (CDCl3) δ: 2.61 (s, 3H, CH3S), 4.66 (dd, 1H, J ) 12.6, 3.2 Hz, rib H5b), 4.84 (ddd, 1H, J ) 7.0, 3.2, 2.4 Hz, rib H4), 4.91 (dd, 1H, J ) 12.6, 2.4 Hz, rib H5a), 5.77 (dd, 1H, J ) 7.0, 5.3 Hz, rib H3), 5.94 (dd, 1H, J ) 5.3, 3.0 Hz, rib H2), 6.32 (d, 1H, J ) 7.3 Hz, H5 pyr), 7.22 (d, 1H, J ) 3.0 Hz, rib H1), 7.30-7.69 (m, 9H, CHar meta and CHar para), 7.86 (d, 2H, J ) 8.5 Hz, CHar ortho), 7.96 (d, 1H, J ) 7.3 Hz, H6 pyr), 8.07 (m, 4H, CHar ortho). 13C NMR (CDCl3) δ: 13.1 (CH3S), 62.6 (rib C5), 69.4 (rib C3), 75.0 (rib C2), 80.1 (rib C4), 92.0 (rib C1), 108.3 (C5 pyr), 128.5, 128.8, 129.6 and 130.1 (3 Car, 6 CHar meta, 3 CHar para), 133.7 (6 CHar ortho), 138.1 (C6 pyr), 164.8 and 172.8 (3 COC6H5 and CdN), 180.0 (CdS). MS m/z 603 ([M + H]+), 359 (100), 297, 123. HRMS (DCI): m/z calcd for C31H27N2O7S2 [M + H]+ 603.1260, found 603.1302. 1-(2,3,5-Tri-O-benzoyl-β-D-xylofuranosyl)-4-methylsulfanyl-1,2-dihydropyrimidin-2-thione (7f). Yellow crystals (yield 83%). Mp: 89-91 °C. IR (KBr): 1728, 1600, 1450, 1260, 1090, 707 cm-1. 1H NMR (CDCl3) δ: 2.65 (s, 3H, CH3S), 4.73 (dd, 1H, J ) 12.3, 4.2 Hz, xyl H5a), 4.87 (dd, 1H, J ) 12.3, 4.2 Hz, xyl H5b), 5.03 (m, 1H, xyl H4), 5.77 (d, 1H, J ) 3.1 Hz, xyl H3), 5.94 (s, 1H, xyl H2), 6.55 (d, 1H, J ) 7.3 Hz, H5 pyr), 6.79 (s, 1H, xyl H1), 7.34-7.64 (m, 9H, CHar meta and CHar para), 7.77 (dd, 2H, J ) 8.5, 1.4 Hz, CHar ortho), 7.92 (dd, 2H, J ) 8.5, 1.4 Hz, CHar ortho), 8.15 (dd, 2H, J ) 8.6, 1.5 Hz, CHar ortho), 8.21 (d, J ) 7.3 Hz, H6 pyr). 13C NMR (CDCl3) δ: 13.1 (CH3S), 61.4 (xyl C5), 74.6 (xyl C3), 80.2 and 81.9 (xyl C2 and C4), 94.2 (xyl C1), 107.5 (C5 pyr), 128.1, 128.5, 128.6, 129.1, 129.7, 129.9, 130.2, 133.5, 133.8 and 134.1 (3 Car, 6 CHar

Efficient Route to Pyrimidine Nucleoside Analogues meta, 3 CHar para, and 6 CHar ortho), 139.3 (C6 pyr), 164.3, 164.4, 166.1 and 172.8 (3 COC6H5 and CdN), 179.4 (CdS). MS: m/z 603 ([M + H]+), 359, 123 (100). HRMS (DCI): m/z calcd for C31H27N2O7S2 [M + H]+ 603.1260, found 603.1267. N,N-Dimethyl-N′-(2,3,4,6-tetra-O-acetyl-β-D-glucopyranosyl)thiourea (8a). Yellow crystals (yield 72%). Mp: 7274 °C. IR (KBr): 1750, 1550, 1229, 1067 cm-1. 1H NMR (CDCl3) δ: 2.03 (s, 3H, COCH3), 2.06 (s, 3H, COCH3), 2.07 (s, 3H, COCH3), 2.08 (s, 3H, COCH3), 3.25 (br s, 6H, N(CH3)2), 3.88 (ddd, 1H, J ) 9.5, 4.6, 2.0 Hz, glu H5), 4.11 (dd, 1H, J ) 12.5, 2.0 Hz, glu H6b), 4.32 (dd, 1H, J ) 12.5, 4.6 Hz, glu H6a), 5.00 (t, 1H, J ) 9.5 Hz, glu H2), 5.08 (t, 1H, J ) 9.5 Hz, glu H4), 5.40 (t, 1H, J ) 9.5 Hz, glu H3), 5.77 (dd, 1H, J ) 8.2, 9.5 Hz, glu H1), 6.41 (d, 1H, J ) 8.2 Hz, NH). 13C NMR (CDCl3) δ: 20.6, 20.8 and 20.9 (4 COCH3 and N(CH3)2), 61.7 (glu C6), 68.5 (glu C4), 71.2 (glu C2), 72.6 (glu C5), 73.2 (glu C3), 83.7 (glu C1), 169.7, 170.7 and 172.2 (4 COCH3), 182.1 (CdS). MS: m/z 435 ([M + H]+), 403, 331 (100), 213. HRMS (CI): m/z calcd for C17H27N2O9S [M + H]+ 435.1436, found 435.1440. N,N-Dimethyl-N′-(2,3,4,6-tetra-O-acetyl-β-D-galactopyranosyl)thiourea (8b). Yellow crystals (yield 82%). Mp: 192-194 °C. IR (KBr): 1746, 1548, 1227, 1084 cm-1. 1H NMR (CDCl3) δ: 2.01 (s, 3H, COCH3), 2.05 (s, 3H, COCH3), 2.09 (s, 3H, COCH3), 2.15 (s, 3H, COCH3), 3.26 (br s, 6H, N(CH3)2), 4.07-4.19 (m, 3H, gal H4, H6a and H6b), 5.19 (d, 1H, J ) 8.1 Hz, gal H2), 5.18-5.21 (m, 1H, gal H5), 5.47 (d, 1H, J ) 2.7 Hz, gal H3), 5.77 (t, 1H, J ) 8.1 Hz, gal H1), 6.44 (d, 1H, J ) 8.1 Hz, NH). 13C NMR (CDCl3) δ: 19.5, 19.6, 19.8 and 20.0 (4 COCH3 and N(CH3)2), 60.1 (gal C6), 66.0 (gal C3), 67.8 (gal C2), 70.0 (gal C5), 71.1 (gal C4), 83.0 (gal C1), 168.7, 169.1, 169.5 and 171.3 (4 COCH3), 181.0 (CdS). MS: m/z 435 ([M + H]+, 100), 403, 331. HRMS (CI): m/z calcd for C17H27N2O9S [M + H]+ 435.1436, found 435.1431 N,N-Dimethyl-N′-(2,3,6,2′,3′,4′,6′-hepta-O-acetyl-β-D-cellobiopyranosyl)thiourea (8c). Yellow crystals (yield 80%). Mp: 112-114 °C. IR (KBr): 1748, 1548, 1230, 1040 cm-1. 1H NMR (CDCl3) δ: 1.98 (s, 3H, COCH3), 2.00 (s, 3H, COCH3), 2.04 (s, 3H, COCH3), 2.05 (s, 3H, COCH3), 2.06 (s, 3H, COCH3), 2.09 (s, 3H, COCH3), 2.12 (s, 3H, COCH3), 3.21 (br s, 6H, N(CH3)2), 3.65 (ddd, 1H, J ) 9.2, 4.6, 2.1 Hz, glu H5′), 3.703.77 (m, 2H, glu H4 and glu H5), 4.03 (dd, 1H, J ) 12.4, 2.1 Hz, glu H6′b), 4.14 (dd, 1H, J ) 11.7, 4.5 Hz, glu H6b), 4.35 (dd, 1H, J ) 12.4, 4.6 Hz, glu H6′a), 4.47 (d, 1H, J ) 8.0 Hz, glu H1′), 4.45-4.55 (m, 1H, glu H6a), 4.91 (t, 1H, J ) 9.3 Hz, glu H2), 4.93 (dd, 1H, J ) 9.2, 8.0 Hz, glu H2′), 5.05 (t, 1H, J ) 9.2 Hz, glu H4′), 5.13 (t, 1H, J ) 9.2 Hz, glu H3′), 5.33 (t, 1H, J ) 9.3 Hz, glu H3), 5.67 (dd, 1H, J ) 9.3, 8.0 Hz, glu H1), 6.37 (d, 1H, J ) 8.0 Hz, NH). 13C NMR (CDCl3) δ: 20.5, 20.7 and 20.9 (7 COCH3 and N(CH3)2), 61.7 (glu C6′), 62.1 (glu C6), 67.9 (glu C4′), 71.5 (glu C2, C2′ and C5′), 72.0 (glu C3 and C3′), 72.9 (glu C5), 74.1 (glu C4), 83.6 (glu C1), 100.6 (glu C1′), 169.0, 169.3, 170.2, 170.4, 170.5 and 172.5 (7 COCH3), 182.1 (CdS). MS: m/z 723 ([M + H]+), 619, 331 (100). HRMS (DCI): m/z calcd for C29H43N2O17S [M + H]+ 723.2282, found 723.2301. N,N-Dimethyl-N′-(2,3,6,2′,3′,4′,6′-hepta-O-acetyl-β-D-lactopyranosyl)thiourea (8d). Yellow crystals (yield 73%). Mp: 123-125 °C. IR (KBr): 1749, 1548, 1231, 1083 cm-1. 1H NMR (CDCl3) δ: 1.96 (s, 3H, COCH3), 2.06 (s, 6H, 2 COCH3), 2.07 (s, 6H, 2 COCH3), 2.12 (s, 3H, COCH3), 2.17 (s, 3H, COCH3), 3.22 (br s, 6H, N(CH3)2), 3.76-3.86 (m, 2H, glu H4 and gal H5), 4.07-4.15 (m, 3H, glu H6b, gal H6a and H6b), 4.20 (dd, 1H, J ) 4.5, 2.2 Hz, glu H5), 4.43 (d, 1H, J ) 7.8 Hz, gal H1), 4.41-4.46 (m, 1H, glu H6a), 4.92 (t, 1H, J ) 9.1 Hz, glu H2), 4.94 (dd, 1H, J ) 10.4, 2.9 Hz, gal H3), 5.11 (dd, 1H, J ) 10.4, 7.8 Hz, gal H2), 5.36 (d, 1H, J ) 2.9 Hz, gal H4), 5.39 (m, 1H, glu H3), 5.69 (dd, 1H, J ) 9.1, 7.9 Hz, glu H1), 6.38 (d, 1H, J ) 7.9 Hz, NH). 13C NMR (CDCl3) δ: 20.6 and 20.9 (7 COCH3 and N(CH3)2), 61.0 and 62.1 (glu C6 and gal C6), 66.7 (gal C4),

68.9 (gal C2), 70.8 and 71.0 (gal C3 and C5), 71.5 and 72.0 (glu C2, C3 and C5), 74.1 (glu C4), 83.6 (glu C1), 100.8 (gal C1), 169.0, 169.3, 170.1, 170.4 and 172.5 (7 COCH3), 182.1 (CdS). MS: m/z 723 ([M + H]+), 331 (100). HRMS (DCI): m/z calcd for C29H43N2O17S [M + H]+ 723.2282, found 723.2296. N,N-Dimethyl-N′-(2,3,5-tri-O-benzoyl-D-ribofuranosyl)thiourea (8e). Yellow oil (yield 75%). Mixture of anomer R and β. Mp: 69-71 °C. IR (KBr): 1726, 1600, 1538, 1269, 709 cm-1. 1H NMR (CDCl3) δ: 3.22 (br s, 12H, N(CH3)2), 4.574.75 (m, 6H, rib H4, H5a and H5b), 5.82-5.92 (m, 4H, rib H2 and H3), 6.39 (d, 1H, J ) 7.3 Hz, NH of one anomer), 6.506.57 (m, 2H, NH of one anomer and rib H1 of one anomer), 6.93 (dd, 1H, J ) 8.5, 4.8 Hz, rib H1 of one anomer), 7.347.51 (m, 12H, CHar meta), 7.51-7.62 (m, 6H, CHar para), 7.89 (dd, 2H, J ) 8.3, 1.3 Hz, CHar ortho), 7.93 (dd, 2H, J ) 8.4, 1.3 Hz, CHar ortho), 7.97 (dd, 2H, J ) 8.5, 1.4 Hz, CHar ortho), 8.04 (dd, 2H, J ) 8.5, 1.4 Hz, CHar ortho), 8.10 (dd, 4H, J ) 7.1 Hz, J ) 1.2 Hz, CHar ortho). 13C NMR (CDCl3) δ: 40.5 (N(CH3)2), 64.3 (rib C5), 70.8, 71.9, 73.4 and 74.1 (rib C2 and C3), 78.8 and 79.4 (rib C4), 84.6 (rib C1 of one anomer), 87.6 (rib C1 of one anomer), 128.5, 128.6, 129.5, 129.7, 129.8 and 129.9 (6 Car, 12 CHar meta and 12 CHar ortho), 133.3, 133.4, 133.7 and 133.8 (6 CHar para), 164.5, 165.1, 165.6, 166.0 and 166.2 (6 COC6H5), 181.9 and 182.1 (CdS). MS: m/z 549 ([M + H]+), 445 (100), 123. HRMS (DCI): m/z calcd for C29H29N2O7S [M + H]+ 549.1694, found 549.1680. N,N-Dimethyl-N′-(2,3,5-tri-O-benzoyl-D-xylofuranosyl)thiourea (8f). Yellow oil (yield 82%). Mixture of anomers R and β. Anomer R or β: Rf ) 0.43 (hexane/AcOEt 6/4). IR (KBr): 1725, 1600, 1536, 1262, 708 cm-1. 1H NMR (CDCl3) δ: 3.20 (br s, 6H, N(CH3)2), 4.64 (d, 2H, J ) 5.3 Hz, xyl H5a and H5b), 4.86 (q, 1H, J ) 5.3 Hz, xyl H4), 5.82 (t, 1H, J ) 3.7 Hz, xyl H2), 5.90 (dd, 1H, J ) 5.3, 3.7 Hz, xyl H3), 6.27 (d, 1H, J ) 7.7 Hz, NH), 6.49 (dd, 1H, J ) 7.7, 3.7 Hz, xyl H1), 7.35-7.65 (m, 9H, CHar meta and para), 7.97-8.03 (m, 4H, Har ortho), 8.07 (dd, 2H, J ) 8.4, 1.3 Hz, Har ortho). 13C NMR (CDCl3) δ: 40.6 (N(CH3)2), 62.5 (xyl C5), 75.3 and 75.7 (xyl C3 and C4), 79.5 (xyl C2), 88.6 (xyl C1), 128.6, 128.7, 128.9, 129.7, 130.1, 133.3 and 133.8 (3 Car, 6 CHar meta, 6 CHar ortho, and 3 CHar para), 165.0, 165.5 and 166.2 (3 COC6H5), 181.6 (CdS). Anomer R or β: Rf ) 0.34 (hexane/AcOEt 6/4). IR (KBr): 1725, 1600, 1536, 1262, 708 cm-1. 1H NMR (CDCl3) δ: 3.21 (br s, 6H, N(CH3)2), 4.56 (dd, 1H, J ) 11.6, 5.8 Hz, xyl H5a), 4.67 (dd, 1H, J ) 11.6, 5.9 Hz, xyl H5b), 4.87 (m, 1H, xyl H4), 5.80 (dd, 1H, J ) 4.2, 1.8 Hz, xyl H2), 5.89 (dd, 1H, J ) 4.2, 1.8 Hz, xyl H3), 6.12 (d, 1H, J ) 9.0 Hz, NH), 7.02 (dd, 1H, J ) 9.0, 4.2 Hz, xyl H1), 7.40-7.70 (m, 9H, CHar meta and CHar para), 8.01 (dd, 2H, J ) 8.6 Hz, J ) 1.5 Hz, CHar ortho), 8.04-8.11 (m, 4H, CHar ortho). 13C NMR (CDCl3) δ: 40.6 (N(CH3)2), 62.4 (xyl C5), 75.3 and 75.6 (xyl C2 and C3), 76.2 (xyl C4), 85.5 (xyl C1), 128.4, 128.5, 128.6, 128.9, 130.0, 133.2, 133.3, 133.8 and 134.1 (3 Car, 6 CHar meta, 6 CHar ortho, and 3 CHar para), 164.1, 165.0 and 166.1 (3 COC6H5), 181.5 (CdS). MS: m/z 549 ([M + H]+), 445, 305, 123 (100). HRMS (DCI): m/z calcd for C29H29N2O7S [M + H]+ 549.1696, found 549.1688.

Acknowledgment. We are grateful to the French Ministry of Education and the CNRS for financial support. Supporting Information Available: General procedures, copies of 1H and 13C NMR for compounds 4 and 5, and copies of 1H, 13C NMR, and 2D NMR (COSY and HMQC) for compounds 7a-f and 8a-f (except COSY of one anomer 8f). This material is available free of charge via the Internet at http://pubs.acs.org. JO034709A

J. Org. Chem, Vol. 68, No. 22, 2003 8587